Creating amphiphilic porosity in two-dimensional covalent organic frameworks via steric-hindrance-mediated precision hydrophilic-hydrophobic microphase separation

Creating different pore environments within a covalent organic framework (COF) will lead to useful multicompartment structure and multiple functions, which however has been scarcely achieved. Herein we report designed synthesis of three two-dimensional COFs with amphiphilic porosity by steric-hindrance-mediated precision hydrophilic-hydrophobic microphase separation. Dictated by the different steric effect of the substituents introduced to a monomer, dual-pore COFs with kgm net, in which all hydroxyls locate in trigonal micropores while hydrophobic sidechains exclusively distribute in hexagonal mesopores, have been constructed to form completely separated hydrophilic and hydrophobic nanochannels. The unique amphiphilic channels in the COFs enable the formation of Janus membranes via interface growth. This work has realized the creation of two types of channels with opposite properties in one COF, demonstrating the feasibility of introducing different properties/functions into different pores of heteropore COFs, which can be a useful strategy to develop multifunctional materials.

Section A. Instruments and methods.

Fourier transform infrared spectroscopy (FT-IR)
Fourier transform infrared spectroscopy (FT-IR) was carried out with a Perkin-Elmer PE-983 spectrometer.The samples were fully dried prior to data collection.

Nuclear magnetic resonance (NMR) spectroscopy
For solution phase NMR, 1 H NMR and 13 C NMR were collected by a JEOL 400 M or an Agilent 500 M instrument.Solid-state 13 C cross-polarization/magic angle spinning (CP/MAS) spectra were collected on Agilent DD2 600 Solid system. 1 H-13 C CP/MAS experiment using a 3.2 mm HFXY MAS probe and a 3.2 mm ZrO2 rotor, the cross-polarization time was 1 ms, the cycle delay was set to 2 s, and the 13 C chemical shift was calibrated using adamantane (38.56 ppm).

Scanning electron microscopy (SEM)
Scanning electron microscopy was carried out using a XL30 FEG and ZEISS GeminiSEM 300 scanning electron microscope.The samples were dispersed over a slice of conductive adhesive adhered to a flat copper platform sample holder and then coated with gold using a sputter 9 coater (ambient temperature, 85 torr pressure in a nitrogen atmosphere, sputtered for 30 s from a solid gold target at a current of 30 mA) before being submitted to SEM characterization.

Transmission electron microscopy (TEM)
Transmission electron microscopy was performed on a JEOL JEM-2100 instrument.
Before the test, the sample powder was dispersed in ethanol to form a suspension.The samples were dispersed over the carbon coated cooper girds with ethanol as solvent.

Thermal gravimetric analysis (TGA)
Thermal gravimetric analyses were carried out on Waters TGA Q500 by heating the samples from 20 to 900 o C under nitrogen atmosphere at a heating rate of 10 o C /min.

Powder X-ray diffraction (PXRD)
Powder X-ray diffraction measurements were carried out with a PANalytical X' Pert Powder system using monochromated Cu/Kα (λ = 0.1542 nm).The sample was spread on the square recess of XRD sample holder as a thin layer.

Nitrogen adsorption-desorption isotherm measurements
The measurements were carried out using a Quantachrome autosorb iQ automatic volumetric instrument.Before gas adsorption measurements, the as-prepared samples (30 mg) were washed with tetrahydrofuran (THF) for 4 h.The samples were activated by degassing at 120 o C for 5 h and used for gas adsorption measurements from 0 to 1 atm at 77 K.The Brunauer-Emmett-Teller (BET) method was utilized to calculate the specific surface areas.By using the non-local density functional theory, the pore size distributions were derived from the sorption data.

Structural modeling and powder X-ray diffraction analysis
Structural modeling was carried out using the Materials Studio 7.0.The predicted structures with eclipsed (AA) and staggered (AB) stacking models were firstly optimized in geometry optimizations by the Forcite molecular dynamics module method, after which the simulated PXRD patterns were determined by the Reflex module.The Pawley refinement of the experimental PXRD was conducted by the Reflex module.

Synthesis of 2-butoxy-5-hydroxyterephthalaldehyde (TPA-Bu)
A mixture of DHTA (1.0 g, 6.0 mmol) and K2CO3 (500 mg, 3.6 mmol, 0.6 eq) in DMF (50 mL) was degassed through three freeze-pump-thaw cycles under an argon atmosphere and was stirred at room temperature for 0.5 h.1-iodobutane was then dropped into the mixture and was stirred at 50 ℃ for about 4 h.After being cooled to room temperature, saturated ammonium chloride solution was added to quench the reaction and the mixture was extracted with dichloromethane.The organic phase was washed consecutively with water and saturated ammonium chloride solution, dried over anhydrous MgSO4, filtered and evaporated.The crude product was purified by flash column chromatograph (PE: EA = 10: l) to give TPA-Bu as yellow powder (481 mg, 35.9 %).

Synthesis of 2-hexyloxy-5-hydroxyterephthalaldehyde (TPA-Hex)
A mixture of DHTA (1.0 g, 6.0 mmol) and K2CO3 (1.0 g, 7.2 mmol, 1.25 eq) in DMF (50 mL) was degassed through three freeze-pump-thaw cycles under an argon atmosphere and then was stirred at room temperature for 0.5 h.1-iodohexane was then dropped into the mixture and was stirred at 50 ℃ for about 4 h.After being cooled to room temperature, HCl (aq. 2 M) was added to quench the reaction and the mixture was extracted with ethyl acetate.The organic phase was washed consecutively, dried over anhydrous MgSO4, filtered and evaporated.The crude product was purified by flash column chromatograph (PE: EA = 5: l) to give TPA-Hex as yellow powder (530 mg, 35.2 %).

Synthesis of 2-phenoxy-5-hydroxyterephthalaldehyde (TPA-Ph)
A mixture of DHTA (300 mg, 1.8 mmol) and K2CO3 (248.4 mg, 1.8 mmol) in DMF (50 mL) was degassed through three freeze-pump-thaw cycles under an argon atmosphere and then was stirred at 0 o C for 0.5 h.Benzyl iodide (392.4 mg, 1.8 mmol) diluted in anhydrous DMF (10 mL) was then slowly dropped into the mixture and the mixture was stirred at 0 ℃ for about 4 h.Then, 12 mL HCl (aq. 1 M) was added to quench the reaction and the solvent was removed by rotary evaporation.The crude product was purified by flash column chromatograph (PE: EA = 20: l) to give TPA-Ph as yellow powder (118.7 mg, 25.8 %).
The crude product was purified by flash column chromatograph (PE: EA = 20: l) to give TPA-Ph as yellow powder (50 mg, 9.1 %).

Procedure for the preparation of COF-Ph
A mixture of ETTA (11.8 mg, 0.03 mmol), TPA-Ph (15.4 mg, 0.06 mmol), and odichlorobenzene (1 mL) in a glass ampoule was sonicated for 10 min and then acetic acid (aq., 6 M, 0.1 mL) was added.The ampoule was sealed after being degassed in a liquid nitrogen bath for 5 min, warmed to room temperature and then kept at 120 o C without disturbance for 3 days to yield a red solid.After being cooled to room temperature, the solvent was decanted and the solid was washed with dichloromethane and acetone for 3 times and then dried under dynamic vacuum at 120 o C for 2 h to afford a red powder (17.9 mg, 70.5%).Anal.Calcd.For C168H120N12O12: C, 80.77; H, 4.81; N, 6.73.Found: C, 78.60; H, 4.85; N, 6.29.

Procedure for the preparation of COF-Na
A mixture of ETTA (9.8 mg, 0.025 mmol), TPA-Na (15.3 mg, 0.05 mmol), and odichlorobenzene (1 mL) in a glass ampoule was sonicated for 10 min and then acetic acid (aq., 3 M, 0.1 mL) was added.The ampoule was sealed after being degassed in a liquid nitrogen bath for 5 min, warmed to room temperature and then kept at 120 o C without disturbance for 3 days to yield a red solid.After being cooled to room temperature, the solvent was decanted and the solid was washed with dichloromethane and acetone for 3 times and then dried under dynamic vacuum at 120 o C for 2 h to afford a red powder (15.5 mg, 66.5%).Anal.Calcd.For C192H132N12O12: C, 82.40; H, 4.72; N, 6.01.Found: C, 77.99; H, 4.58; N, 6.09.

Procedure for the preparation of SIOC-COF 2
A mixture of 4,4',4'',4'''-(ethene-1,1,2,2-tetrayl)tetraaniline (ETTA, 30 mg, 0.076 mmol), terephthalaldehyde (TPA, 20.5 mg, 0.153 mmol), and 1,4-dioxane (1 mL) in a glass ampoule was sonicated for 10 min and then acetic acid (aq., 6 M, 0.1 mL) was added.The ampoule was sealed after being degassed in a liquid nitrogen bath for 5 min, warmed to room temperature and then kept at 120 o C without disturbance for 3 days to yield a yellow solid.After being cooled to room temperature, the solvent was decanted and the solid was washed with THF and acetone for 3 times and then dried under dynamic vacuum at 120 o C for 2 h to afford a yellow powder (40.6 mg, 90.2%).
After being cooled to room temperature, the solvent was decanted and the solid was washed with THF and acetone for 3 times and then dried under dynamic vacuum at 120 Supplementary Fig. 23 FT-IR spectra of COF-TAB-Hex and its monomers.Supplementary Fig. 24 FT-IR spectra of SIOC-COF and its monomers.Note: The small shoulder on the main diffraction peak of the SIOC-COF membrane marked with * could probably be attributed to a partial staircase-like stacking of the COF layers synthesized by interfacial-polymerization.
membrane Supplementary Fig. 33 Comparision between FT-IR spectra and PXRD patterns of the powder and membrane of COF-TAB-Hex.Comparison between FT-IR spectra and PXRD patterns of the powder and membrane of SIOC-COF.

Fractional atomic coordinates of the COFs. SupplementaryTable 1 .
Fractional atomic coordinates for the unit cell of COF-Bu with eclipsed stacking.

Table 2 .
Fractional atomic coordinates for the unit cell of COF-Ph

Table 3 .
Fractional atomic coordinates for the unit cell of COF-Na with eclipsed stacking.

Table 4 .
Fractional atomic coordinates for the unit cell of COF-TAB-

Table 5 .
Fractional atomic coordinates for the unit cell of SIOC-COF with eclipsed stacking.